Flohe, Giertz and Bechmann discuss the use of free-radical scavengers as anti-inflammatory drugs in Handbook of inflammation, Volume 5: The Pharmacology of Inflammation, pages 255-281 (Elsevier Science Publishers BV, 1985). Superoxide anion is said to serve an indispensable purpose in the killing of phagocytosed micro-organisms. Superoxide anion and reaction products such as hydroxyl radical are said to be deleterious in the extracellular environment, possibly leading to self-maintenance of the inflammatory reaction and to tissue damage. The authors report the successful treatment of a variety of inflammatory conditions by injection of the enzyme superoxide dismutase (SOD), which catalyses the reaction: EQU 2O.sub.2..sup.- +2H.sup.+ O.sub.2 +H.sub.2 O.sub.2
The authors point out a number of difficulties in the concept of scavenging free radicals by drugs rather than by enzymes. In particular, the reaction of free radical and scavenger generates a new free radical. If this is as reactive as the original radical, no benefit has been obtained. If it is less reactive, it may migrate away from the wound site and cause damage in a previously healthy area. The authors conclude that scavenging of highly reactive radicals in vivo is neither feasible nor desirable.
U.S. Pat. No. 4,837,024 describes compositions which enhance and promote the wound healing process and which comprise suspensions of the fibrous protein, collagen, and of a polysaccharide, namely a glycosaminoglycan. The glycosaminoglycan is one which exhibits chemotaxis for fibroblasts or endothelial cells; the preferred glycosaminoglycans are said to be heparin, heparan sulphate and alginate, although it should be noted that alginate is not in fact a glycosaminoglycan.
International Patent Application WO 91/11205 describes biopolymers which can be formulated into wound dressings which improve wound healing. The biopolymers are polysaccharides which contain at least 70% mannuronic acid residues, for example certain types of bacterial alginate or of oxidised guar gum or oxidised mannan.
International Patent Application WO91/12267 describes metal:peptide complexes possessing anti-oxidative and anti-inflammatory activity. The metal is typically copper (II) or manganese (II) and the peptide is a tripeptide or tetrapeptide. These soluble complexes can be used as active therapeutic substances and in the preparation of medicaments for the treatment of wounds or inflamed areas. The complexes are said to mimic the activity of SOD.